On Tue, Sep 7, 2010 at 5:54 AM, Sam Tobin-Hochstadt <sa...@ccs.neu.edu> wrote: > On Mon, Sep 6, 2010 at 10:28 PM, Eli Barzilay <e...@barzilay.org> wrote: >> On Sep 6, Sam Tobin-Hochstadt wrote: >>> On Sun, Sep 5, 2010 at 5:30 PM, Eli Barzilay <e...@barzilay.org> wrote: >>> > >>> > I think that this is the type for `file-or-directory-modify-seconds': >>> > >>> > (case-lambda >>> > [String -> Exact-Nonnegative-Integer] >>> > [String (Option Exact-Nonnegative-Integer) >>> > -> (U Exact-Nonnegative-Integer Void)] >>> > [String (Option Exact-Nonnegative-Integer) (-> Any) >>> > -> Any]) >>> >>> Probably you want something more specific that handles the [String >>> Integer] and [String False] cases separately. >> >> Yeah, but that's the part that I can never remember. This: >> >> (U (String -> Exact-Nonnegative-Integer) >> (String False -> Exact-Nonnegative-Integer) >> (String Exact-Nonnegative-Integer -> Void) >> (String (Option Exact-Nonnegative-Integer) (-> Any) -> Any)) >> >> is more precise, but IIRC, it's not equivalent to the above -- ? > > Why does everyone always want to use union for this? Everything you > wrote there is correct, except that `U' should be `case-lambda'.
There is something to be said for making the things that everyone writes first be the thing they should write. It is natural to me to think of a function with multiple arrow types as a union of some arrow types. Would it be so hard for Typed Racket to see a union of all arrows and just consider that the same as case-lambda? Is that wrong? If it is fundamentally wrong, some better form of explanation in the docs seem warranted. Jay > > You can't use that type in `require/typed', though, since the contract > library doesn't accept `case->' contracts like that. > -- > sam th > sa...@ccs.neu.edu > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/dev > -- Jay McCarthy <j...@cs.byu.edu> Assistant Professor / Brigham Young University http://teammccarthy.org/jay "The glory of God is Intelligence" - D&C 93 _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
